The use of plant growth promoting fluorescent lamps for the illumination of tropical fish has gained wide acceptance due to the vivid color enhancement of red and blue colored fish. However, these lamps emit insufficinet energy in the 520 to 590 nanometer band and their overall color rendition makes them unsuitable for the illumination of marine tropical fish which exhibit a greater variety of colors and particularly some bright yellows. In addition to color enhancement, it is also desirable to provide an illumination source which would stimulate the growth of life sustaining brown, red and green algae for these seawater tropical fish.